That One Where Stiles Is Possessed By A Demon
by Mary Jane Parker
Summary: That one where Stiles is possessed by a demon named Saul while on a college road trip. Heavy on the Sterek, light on the SPN Demon mythos. Enjoy!
1. Chapter 1

It's pretty brilliant on the demon's part, Stiles has to admit. Everyone knows his stomach's a bottomless pit, so when the thing insists on multiple stops at fast food joints after their visit to the Winchester Mansion no one thinks twice about it. They complain and roll their eyes, and Derek does that thing where he threatens bodily harm (which is more the mandatory reaction these days rather than something he's _actually_ going to do), but they're not suspicious. And as the demon inside Stiles happily munches down close to twenty of those tiny White Castle burgers, his own order of fries, and then half of Scott's the car slowly starts to smell like a burger joint.

No chance for any of those sensitive werewolf noses to pick up the slight sulfuric smell already seeping out of him.

Not that it'd mean anything to any of them anyway. Stiles is the research king. He's the one who started looking into other instances of the supernatural, figuring that if his best friend is a werewolf then there _had_ to be other stuff out there. Hence the side trip to the Winchester Mystery House after their last UC school visit. Stiles is fairly good at getting what he wants, and it's possible that in the past few months, Derek has become slightly more pliable.

Of course now, Stiles is wishing like hell that the Sour-Wolf had reared it's ugly, yet strangely endearing, head and put his foot down in the face of his incessant begging for stops and side trips. Instead Derek had simply looked away from the road for a moment and said –not even growled!-, "Fine. Just stop _talking_ about it." And Stiles had promptly shut up while proceeding to grin like a maniac all the way from Oakland.

The demon, who calls himself Saul, is _still_ grinning though for entirely different reasons now, as he shoves one last burger down Stiles' throat.

_Dude, we have lacrosse practice on Monday, h_e thinks, knowing the thing wrapped around his brain can hear him.

It takes a moment before Saul replies. _Really? That's what you're worried about?_

_I'm trying to stay calm. _He's doing a remarkable job of it too, if he does say so himself. But compared to facing down an Alpha, this is nothing. This is something he can fix. Or, rather, it's something his Pack can fix. Stiles can't do so much as wiggle a pinky toe, but it's still not as bad as trying not to wet himself while looking Peter in the eye.

Granted, he can't pee by choice or any other way right now, but still.

_Not as terrifying as an Alpha, eh?_

Right, no secrets here. _No offense, man, but Peter didn't __**need**__ to keep me alive. You're living inside me and since you obviously chose the smartest, strongest, most devastatingly handsome one in the group, I'm guessing you have a healthy sense of self preservation meaning you're not going to let anything happen to me._

Saul laughs and it sounds weird and echoy with the noise not coming from any particular source. _I like you, meatsack_.

_Hey! I'm not the one who just ate enough White Castle to feed Harold and Kumar._

_I like you_, Saul repeats. Stiles imagines he's grinning_. But I want to make one thing clear_...

Stiles can hear Derek sniff the air pointedly in thee driver's seat, and when he turns to look at Stiles his normal glare softens into a scowl. "Your nose is bleeding." On to his favorite BSG tee, no less. Maybe this thing really is evil.

Alison is disentangling herself from Scott in the back seat to search or the pile of napkins came with the meal, and Scott leans forward along with Jackson and Lydia in the far back. "You okay, man?"

Stiles can't answer and he thinks Saul must be grinning again. _...I own you._

And that's when everything goes black.

Yeah, so the theory about needing to keep him alive? That's a bust. Turns out the demon can keep him alive supernaturally even after a fatal blow. And, as he proves one more time during trigonometry, that fatal blow doesn't have to come from someone like Kate Argent. Stiles quickly decides there's nothing more alarming than the feeling of his heart straining to beat, as if a massive hand has clamped down around it.

He's still catching his breath when they leave class. Scott and Jackson flank his sides and Lydia and Alison join them after coming out of whatever ridiculously advanced Math they're taking this semester. (Stiles could have joined them, the school guidance counselor says, if his motivation didn't jump ship everytime something shiny glinted in his direction.)

"You look pale," Lydia says bluntly, bumping shoulders with him as they sit down in the cafeteria.

Stiles wants to tell her that she'd look pale too if she had Casper The Not-So Friendly Ghost hitching a ride in her skull, but he keeps his mouth shut because at the moment he he has control of said mouth and he wants to keep it that way as long as he can. It's a shitty deal, but so long as he doesn't say anything Saul lets him have the school day and a little time after- Probably because AP European History bores demons as much as it does regular humans. There're the little things though, like the pressure on his heart during trig, that remind him to reign in the snarky comments.

_Besides_, Saul chimes in. _I'm not a ghost. One hundred percent demon, kiddo._

_I hate you_.

_We're having fun, Genim_. Stiles rolls his eyes at the use of his first name, prompting strange looks from the rest of his pack. Lydia is staring at him expectantly.

"I'm fine," he mutters.

The demon huffs. _That sounded convincing_.

Stiles is busy cursing the fact that he hadn't shared the details of any of his research with the rest of the pack. Better to look crazy for believing in ghosts –sorry, _demons_- than to be possessed with no chance of anyone figuring out what was going on with him. The girls are way more observant that Scott or Jackson, but he really doesn't think that either of them are going to immediately jump to a diagnosis of demonic possession.

_Probably not, _Saul agrees.

_Shut up._

_Think they're brushing up their Latin?_

He's probably the only one who knows any Latin aside from Derek, the closeted mythology buff.

_Who we'll just be staying away from. _

_Good luck with that. _They're all supposed to gather at Lydia's house later for a pack meeting and even though he's human, his absence is going to be noticed. In fact, he's probably going to wake up at some point that night to a looming, Derek shaped shadow in his window that night.

Saul smirks. _Normally you'd be into that. _

His face turns bright red and while Saul laughs hysterically (at least _someone_ finds this situation funny...) Scott and Alison exchange a look. "Uh, Stiles, seriously... how much adderall have you been taking lately?"

Okay, the fact that they've come to the conclusion that it's an adderall issue _is_ kind of funny. Ladies and gentlemen, the werewolf pack of Beacon Hills.

Stiles sighs, pushing away an untouched lunch tray before reaching for his bag. "I'm fine. I'll see you in bio, okay?"

"And at my house at six," Lydia says pointedly. "Be on _time. _I'm going to Stamford whether Derek wants to hear it or not, but it's going to go over a lot better if he's not pissy because you're consistently distracted and late."

"You haven't even applied yet," Jackson points out.

"It's an inevitability," she answers, looking at him as if he's crazy to think anything else. "He might as well get used to the idea now."

Excited college talk trumps the 'how much aderall are you taking' discussion and Stiles takes the opportunity to slip out of the cafeteria. He has bio and a a study hall period left, but he turns and heads for the doors that lead out into the parking lot where his jeep is parked.

_Corrupting influence? Check,_ Stiles feels Saul begin to wrest back control of his body . He's no longer the one walking back to the truck. _Any funny business trying to take back your meatsack and I'm wrapping this car around a pole. That clear?_

_Crystal_. Because despite it all, Stiles likes being alive.

The demon grins as he turns the key in the ignition. _Buck up, Genim. I'm a fair demon. It's not all take, take, take on my end. I've got a little something for you too. _Saul has a little fun, revving the poor Jeep's engine while Stiles winces mentally . His girl can't handle this kind of stress.

_That's maybe the least reassuring thing I've heard all day, and I'm including you telling me I'll 'get over' near cardiac arrest. Where're we going?_

Saul looks up, adjusting the rear view mirror. Stiles watches has his eyes blink once, twice, and then open black. No iris, no pupil, just deep pools of black nothingness that make his face and the grin on his lips seem far more sinister than he could have every hoped to achieve himself.

Not that he ever hoped for that kind of thing.

His eyes blink again and suddenly his face is his own again, but Saul keeps his gaze locked on the mirror so that Stiles can see himself. _We're going to the cemetery. _He says, as if it should have been obvious. _ I told you. Our partnership, kiddo? It's give and take, and it's time for a little give. You're a lucky one... it's not everyone that gets themselves possessed by a crossroads demon._

Saul relaxes in the seat, one hand on the wheel as they pull out of the school parking lot. His eyes flick back up to the mirror. _Now... Tell me about your mother._


	2. Chapter 2

He's never thought about it before, but now –now that he has more than enough time for contemplative thoughts in the solitary confinement that is his brain- Stiles realises that even if he and his friends weren't all linked through the whole lycanthropy thing, they still had some epic abandonment issues in common. It's easy to blame the pack's touchy-feely nature on their wolf sides, but there's more to it than that. With an average of .5 parents and other involved family members between them, it's no wonder they cling to each other the way they do.

They're family, and a close knit one at that, but it doesn't erase the fact that Scott's father walked out on him, that Lydia's parents insist on trying to buy her affections, that Derek's family was murdered, that his own mother died-

_A little emo, don't you think?_

He's going to be like Derek soon, with his face set in a permascowl. And being demonically possessed at the moment, he thinks he's entitled to one or two Evanescence moments now and then.

_I thought you would have cheered up by now. My offer still stands. _Saul goes on. _Think of it as a gift. I'm not even asking for your soul._

No, he's asking for permanent residence in Stiles' head. Is 'asking' even the right word when a supernatural thing shoves itself into your brain without so much as a please or thank you?

_I **tried** to say thank you. _

Stiles very pointedly ignores that and tries to lose himself in the Edgar Allen Poe story he couldn't have told anyone the plot of even under threat of having his throat ripped out. Normally he performs rather well under that kind of pressure, but the consistent voice in his brain is like having an old Britney Spears song stuck in his head and being forced to go through the day with nothing but the refrain on repeat. (Not that he's ever listened to enough Britney Spears for that to be a problem, of course.)

_It's pretty selfish of you, if you think about it. _There's no chance he's getting anything done tonight.

_I like Beacon Hills. I like you. I like your furry friends- especially the broody one. I'm gonna be sticking around, lighting some fires, causing some trouble. Might as well get something out of it for yourself. If **you **don't say yes, I could always ask your dad. What do you think he'd say? _

A few whiskeys in and his dad'll say and agree to anything where his mother is concerned. It's the only time he talks about her and most of the time Stiles can't bring himself to answer. Probably because he's always sober. _That's what I thought. Drinking after work at the kitchen table and his darling son asks him if he'd do __**anything**__ to bring his wife back from the great beyond... it's almost too easy._

If Stiles had been in control of his own body he wouldn't have been able to walk through the Beacon Hills cemetery as calmly has he had. Even regulated to the small corner of his brain that he was, he'd been a wreck as Saul strolled easily through the grass. The demon knew the way; Stiles may have avoided the place but the path to his mother's grave was still firmly ingrained in his mind. All Saul had to do was look for it.

Damn if it wasn't an odd feeling to want to throw up while having no stomach to do it with. Saul sat them down cross legged in front of his mother's grave and Stiles would have killed to be able to do _something. _Vomitting or crying would have been better than just allowing this.

Saul had only sighed, reaching out to trace his fingers over the lettering on the headstone. "If it makes you feel better," he'd said aloud. "Just remember you're not 'allowing' me to do anything."

_Shouldn't the grass be slowing turning brown and dying while we sit here? I know how these things work_, Stiles retorted. His attempts at defiant humor were halfhearted at best with Saul keeping their gaze focused straight ahead. Stiles wished his eyes would blink and obscure 'beloved wife and mother' if only for a second. Otherwise he was going to keep reading it and become more and more aware of the barely healed wounds the words were reopening and the grief he had no way of expressing.

"Chill, kiddo." Saul pulled his hand back but kept his eyes on the grave. "Calm down. Bouncing around in there isn't getting you you've got nothing to worry about."

At the time it had seemed stupid to point out that that was in no way true. _Why are we here? _

"You don't know what I do." Stiles felt his lips pull up into a grin.

_Fill in for the Ghost of Traumatic Experiences Past?_ He would have been licking his lips nervously if he'd been able. Possibly running his fingers through the fuzz on his head if only to have something to do. _Because you're doing a bang up-_

"I could bring her _back_."

For once, Stiles shuts up.

He hasn't said a word since they left the cemetery, and though it's hard to ignore something that's living in your brain Saul is hard pressed to get a word out of him as he stares intently at his English homework. But he's shaking now, and his chest is tight, and there may or may not be three wet splotches on the page of his book and- oh shit. Yeah. He's crying. Quiet and slow at the start, but tears are making their way down his face at a steady rate. It's probably a good thing, Stiles tells himself. Not as if he can just cry whenever he wants these days. His body isn't his own anymore, so God only knows when the next time he'll be able to pull his knees to his chest and bury his face in his hands like this.

It isn't that Stiles hasn't wished to bring his mom back from the dead a million and one times and then some since she'd died. It's more that it's never gone quite like this, because apparently wishes can take a whole new spin once your best friends all end up as werewolves and you find out there're things out there that can actually _grant_ said wishes. And not just your wishes either.

Saul's right, his dad would do anything to have his mother back. Even inadvertently sell his soul to a demon disguised as his son.

_Five minutes. _The demon sounds disgusted._I can't take more than five minutes of this. Pull yourself together, Genim. We're leaving._

He can't reply past the lump in his throat and doesn't want to anyway. If he's only got five minutes he's not going to waste them arguing with Saul. As undignified as sobbing alone in his bedroom is, it's better than being locked up in his head unable to express anything while a demon defiles his mother's burial site.

The problem is, Stiles isn't going to say yes. He's not going to let Saul bring his mom back from the beyond. He doesn't believe the horror stories Saul told him in the cemetery, because he _knew _his mother, and he knows that there's no way in hell that she would end up in... well, _Hell_. So everything Saul told him –the eternal torture, damnation, and suffering- is complete BS. His mother's in Heaven. She's there and yeah, it sucks that she's not there hugging him while he cries into his jeans, but using a demon to bring her back? It _reeks_ of bad idea. Epically bad. Scott-level bad.

Besides, he's seen enough _Buffy_. You don't just go around ripping souls back down from Heaven.

But if he doesn't say yes, someone will. His dad won't know what hit him, and in ten years...

"Shit," Stiles mumbles, rubbing at his eyes with the heel of his palm. "Shit, shit._ Shit_."

Saul laughs that echoy head-laugh that Stiles is beginning to absolutely hate. _I like you so much, I'm even willing to give him fifteen years._

"Shut up."

_Really? Three hours of the silent treatment later and that's all you come up? Is it that hard to say 'thank you'?_

"Shut _up," _he says through gritted teeth.

There's a headache blooming at the base of his skull, his eyes doing this weird burning and throbbing thing that only happens when he gets likes this, and his throat is getting sore because crying turns him into some weird mouth breather what with all the snot.

There's a lot of snot.

_Ninety seconds, Genim._

Ninety seconds isn't going to be enough time for Stiles to undo the damage Saul had done, taking him to that graveyard. The wounds are raw again, and as much as he'd like to pull himself together and not give the demon the pleasure of retaking his body while he's a pathetic mess, it's actually impossible. He's _still_ crying and with his dad working a double shift that night, he would have happily cried himself to sleep.

_Sixty seconds. This is really sad, y'know. I'm trying to-_

"Can you please stop talking?" Stiles hisses.

"I didn't say anything."

His head jerks up toward his window. The window he doesn't lock anymore because even though he complains day in and day out about werewolves who don't understand how front doors and doorbells work, Stiles secretly reads Derek's refusal to enter his house through any other way as a trust thing. He's not climbing in to Scott or Jackson's bedroom in the middle of the night. Just his. And tonight, Derek's timing is perfect.

"Derek, I need you-"

_Oh no you don't._

Suddenly Stiles can't even wiggle his own toes.


End file.
